The present invention relates to rims for bicycle wheels with tubeless tires.
In particular, the invention regards a rim for a bicycle wheel with tubeless tire, of the type comprising:
a radially inner peripheral wall;
a radially outer peripheral wall;
two circumferential side walls which connect together said outer wall and said inner wall,
in which said side walls extend radially outwards beyond said outer peripheral wall, forming two anchoring ribs for a tubeless tire; and
a valve body rigidly connected to said inner and outer walls for blowing inflation air into the chamber defined between the tire and said outer peripheral wall of the rim.
A rim of the type specified above is, for example, illustrated in FIG. 2 of the European patent application EP-A-0 790 141. In this known solution, the valve body is directly connected to the inner and outer peripheral walls of the rim.
The purpose of the present invention is to provide a rim of the type specified above which presents a relatively simple and inexpensive structure, enables easy and fast operations of assembly of the tire, guarantees perfect tightness of the chamber defined between the tire and the outer peripheral wall of the rim, and, finally, is able to use, as valve body, a valve body of the standard type normally used for bicycle wheels with tires provided with inner tubes.
With a view to achieving the above purposes, the subject of the present invention is a rim of the type specified at the beginning of the present description, further characterized in that said valve body is a valve body of a standard type used for bicycle wheels with tires provided with inner tubes, and in that said valve body is connected to said inner and outer walls of the rim by means of an intermediate tubular element which is mounted inside two holes facing one another that are made in said inner and outer walls and which presents a portion protruding radially beyond said inner wall in the direction of the axis of the rim, the valve body being secured to said portion.
Preferably, the valve body has an external surface with a threaded portion screwed inside an end threaded portion of the internal surface of the intermediate tubular element.
In one first embodiment, the intermediate tubular element has its radially external end bonded or welded to the outer peripheral wall of the rim. In greater detail, in said embodiment the intermediate tubular element is hermetically bonded or welded to the circumferential edge of the hole in the outer peripheral wall of the rim, as well as to the circumferential edge of the hole in the inner peripheral wall. Furthermore, preferably the radially external end of the intermediate tubular element has a front surface that is substantially flush to the external surface of the outer peripheral wall.
In a second embodiment, the intermediate tubular element is instead connected in a disconnectable way to the rim. In a first example of implementation of said second embodiment, the intermediate tubular element has a radially external end portion mounted in a removable way in a bushing which has its ends fixed, preferably bonded or welded, inside the aforesaid holes facing one another of the outer peripheral wall and inner peripheral wall of the rim. In addition, between the intermediate tubular element and the aforesaid bushing there are set sealing means, for example consisting of one or more O-rings which are mounted inside peripheral grooves of the intermediate tubular element and are pressed into contact with the internal surface of the aforesaid bushing. In the aforesaid first example of implementation of the second embodiment, the intermediate tubular element is screwed inside the bushing and has an annular contrast surface that engages the radially internal end surface of the bushing.
In a second example of implementation of the second embodiment of the invention, the intermediate tubular element has a widened head that rests on the external surface of the outer peripheral wall of the rim and a threaded portion protruding beyond the inner peripheral wall, in the direction of the axis of the rim, on which a nut is screwed, so as to pull the aforesaid head against its resting surface.
In a second example of implementation of the second embodiment, the aforesaid bushing is not present, and the intermediate tubular element is engaged through the aforesaid holes facing one another of the inner and outer peripheral walls of the rim and has a widened end head that rests on the external surface of said outer peripheral wall and a threaded portion that protrudes beyond the inner peripheral wall, in the direction of the axis of the rim, and on which a nut is screwed so as to pull the aforesaid head against its resting surface. Preferably, between said head and said resting surface there are set sealing means, for example consisting of an adhesive, or else an O-ring mounted inside a front annular groove made in the external surface of the outer peripheral wall, along the edge of the respective hole.
Thanks to the above-mentioned characteristics, the invention affords numerous advantages. First of all, the valve body used in the rim according to the invention may be a valve body of a standard type used for rims with tires provided with inner tubes. In the second place, the structure of the rim is simple and inexpensive and enables simple and fast operations both of assembly of the tire and of assembly of the valve body. Finally, in the case of the second embodiment, in which the aforesaid intermediate tubular element is connected in a removable way to the rim, the invention also enables easy and fast conversion of the rim in such a way as to adapt it to a tire provided with inner tube. In this case, in fact, it will be sufficient to remove the intermediate tubular element and mount the inner tube with the corresponding valve body in the traditional way, inserting the valve body through the two holes facing one another that are made in the outer and inner peripheral walls of the rim, as well as through the aforesaid bushing in the examples of embodiment where the latter is present.